Sodium hydride → 1alpha,3beta-Bis(tert-butyldimethylsilyloxy)-17-(tert-butoxycarbonylmethoxymethyl)androsta-5,7,16-triene

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Reaction Steps

A solution of 1α,3β-bis(tert-butyldimethylsilyloxy)-17-(hydroxymethyl)androsta-5,7,16-triene (1.0 g, 1.84 mmol), sodium hydride (60% in oil, 220 mg, 5.50 mmol), 15-crown-5 (400 mg, 1.82 mmol) and t-butyl bromoacetate (0.55 ml, 3.69 mmol) in tetrahydrofuran (20 ml) was stirred at an external temperature of 88° C. for 1 hour and 15 minutes. The reaction mixture was diluted with ethyl acetate and filtered through CELITE. Water was added dropwise to the filtrate under ice cooling, followed by washing with saturated aqueous sodium chloride. The organic layer was dried over anhydrous magnesium sulfate. After evaporation under reduced pressure to remove the solvent, the resulting residue was purified by column chromatography (hexane:ethyl acetate=20:1) to give the titled compound (946.6 mg, 78%) as a colorless oil.

Provenance & Evidence